i have a xb 9 sx city with a thunderstorm engine can anyone tell me what size my headers are where they go into my end can as i want to buy a race can and all the ones ive seen are 50 mil but i think mine is bigger than that and dont want to take off the belly pan unless i have to just to check the size .

Measure it yourself would be the wise thing, and you don't even need to take the belly pan off.

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In a purple fug

tried to measure it with a pair of verniers myself but cant with the belly pan on !i wouldnt have asked if it was that easy .

What year is the bike (date of manufacture on VIN sticker)? What does the oil pump cover look like?

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08 Specialized Langster

I measured mine with a piece of string.............

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In a purple fug

it says jul 07 the oil pump cover is different to my mates 03 xb 9 mine is bigger and oval ish shaped

i wanted to know the size of the bore not the cercumferance

When you say bore, do you mean the diameter?
The circumference divided by Pi (3.142), will give you the diameter.

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In a purple fug

yeah its the diamiter or external bore i was after thanks for your maths will do .